Upgrading PHP

Upgrade

Gathering information I have on installing/upgrading PHP on CentOS7

I see that we have multiple versions of php installed on mseas. I don't think the simple installations below (via YUM) will work.

Instructions for installing PHP on CentOS: https://linuxstans.com/how-to-install-php-centos/
Some specific information on the Remi repository (for more advanced PHP)
- Repository home page: http://rpms.remirepo.net/
- CentOS 7 packages: http://rpms.remirepo.net/enterprise/7/
- at this writing, the latest version of PHP 8.2 was: http://rpms.remirepo.net/enterprise/7/php82/x86_64/repoview/
List of PHP extensions required by WordPress: https://make.wordpress.org/hosting/handbook/server-environment/#php-extensions
WordPress blurb on updating PHP: https://wordpress.org/support/update-php/
A link that contains some notes on earlier issues we had with PHP and mysql: http://mseas.mit.edu/download/phaley/cluster/Upgrade_2018_2019/kerberos_wordpress.html

A related issue is the compatibility of WordPress and the themes/plugins we use with updated versions of PHP. Running the "PHP Compatibility Checker" plugin on WordPress gives 3 warnings for the plugin "PostMash Custom" (but clean bills of health on everything else):

FILE: /srv/www/htdocs/wp-content/plugins/postmash-custom/myjson.php
----------------------------------------------------------------------------------------------
FOUND 0 ERRORS AND 3 WARNINGS AFFECTING 3 LINES
----------------------------------------------------------------------------------------------
 133 | WARNING | Use of deprecated PHP4 style class constructor is not supported since PHP 7.
 783 | WARNING | Use of deprecated PHP4 style class constructor is not supported since PHP 7.
 797 | WARNING | Use of deprecated PHP4 style class constructor is not supported since PHP 7.
----------------------------------------------------------------------------------------------

Once we upgrade PHP to version 8.x there is a reasonable risk that these warnings will become errors and I doubt that the "PostMash Custom" plugin will be updated:

WordPress "PostMash Custom" plugin page: https://wordpress.org/plugins/postmash-custom/
"PostMash Custom" plugin home page(dead): http://opperud.com/postmash_custom

Moving forward, we could

Just blindly try with PHP 8.2 (assuming we install that separately from the other PHP versions so we can go back if needed).
Determine if we actually use the "PostMash Custom" plugin
- If yes,
  - estimate how much time it would take to fix this ourselves
  - find replacement options and estimate time to replace "PostMash Custom"
- If no, I'd suggest removing the "PostMash Custom" plugin
Just upgrade to PHP 7.4

A Reply From Geof Newton (ZTech)

The PHP question is actually pretty simple :-) – I’ve had no end of incompatibility and stability problems with v8 so it’s highly recommended by pretty much everyone to go to 7.4 and ignore that 8 exists for now.